In known single-use cameras, a camera body supports a number of photographic components such as a viewfinder, a taking lens, a shutter mechanism and a film advancing and metering mechanism. The body also includes a pair of chambers for holding a film cassette and a take-up spool, respectively, on opposite sides of an exposure gate. To create a lighttight seal, a pair of covers are attached to the front and rear of the camera body.
Typically, a film cassette is loaded into the film cassette chamber of the camera body and the film is prewound from the cassette onto the take-up spool allowing the film to be drawn or wound back into the film cassette during film exposure. Upon exposing all the film, the cassette can then be withdrawn from the camera body by the photofinisher.
In the assembly of many known single-use cameras, the rear cover must be fitted to the remainder of the camera prior to prewinding of the film onto the take-up spool. This fitting is required in order to maintain proper film registration within the camera body to the sprocket wheel which engages the edge perforations of the film. It should be readily apparent that if film registration is not maintained, then the camera will not operate in a functional manner.
The attachment of the rear cover to the remainder of the described camera constitutes a permanent seal. For each attachment, there is a need to provide a lighttight camera at final assembly such as by attachment means such as snaps, hooks, ultrasonic sealing or press fitting members, prior to rewinding of the film due to the need to provide a lighttight camera. In the case of those cameras using press fitting members, considerable downward force is required to fully seat the back cover to the rear of the camera body. Application of this force, if repeated hundreds of times per day by an operator in a manual assembly environment, could lead to repetitive motion trauma types of injuries.